Webservices

INTRODUCTION TO WEB SERVICES Gerard Sylvester

Web Service

A Web Service is a network accessible interface to application functionality, built using standard Internet protocols

A Web Service exposes functionality to a

consumer

Over the Internet or intranet

A programmable URL

Functions you can call over the Internet

Web service simplified Application Code Application Client Web service Platform and language specific communication Platform and language agnostic communication abstraction layer

Web Service

Based on Web standards

HTTP/(S), XML, SOAP, WSDL, UDDI

Can be implemented in any language on any platform

Component-like, reusable

Not tied to any platform / languages

Components of a Web Service

A standard way for communication (SOAP)

A uniform data representation and exchange mechanism (XML)

A standard meta language to describe the services offered (WSDL)

A mechanism to register and locate WS based applications (UDDI)

The Web Service architecture Service Registry Service Provider Service Consumer Publish Find Bind

Underlying Technology Web Service Stack Ubiquitous Communications: Internet Universal Data Format: XML Wire Format: Service Interactions: SOAP Description: Formal Service Descriptions: WSDL Simple, Open, Broad Industry Support Directory: Publish & Find Services: UDDI Inspection: Find Services on server: DISCO

Underlying Technology Web Service Stack Directory http://www.uddi.org UDDI DISCO WSDL SOAP Inspection http://www.ibuyspy.com/ibuyspy.disco Description http://www.ibuyspy.com/ibuyspycs/InstantOrder.asmx?wsdl Wire Format Locate a Service Link to Discovery Document (XML) Request Discovery Document Return Discovery Document (XML) Return Service Description (XML) Return Service Response (XML) Request Service Request Service Description Web Service Client UDDI or other directory service Web Service

Universal Description, Discovery and Integration (UDDI) Protocol

Enables enterprises to quickly and dynamically discover and invoke Web Services both internally and externally

Yellow pages of Web services

Examples

www.uddi.org

www.biomoby.org

www.xmethods.com

Simple Object Access Protocol (SOAP)

SOAP is a lightweight (XML-based) protocol for exchange of information in a decentralized, distributed environment. It consists of mainly of:

an envelope that defines a framework for describing what is in a message and how to process it

relies heavily on XML standards (schemas & name spaces)

The SOAP message structure SOAP Envelope SOAP Header Header Block Message Body SOAP Body Fault Handlers

Web Service Definition Language (WSDL)

WSDL is an XML format for describing network services operating on messages containing either document-oriented or procedure-oriented information.

It defines Web Service as collection of network endpoints or ports .

The following is a list of Web service markup languages .

BEEP - Blocks Extensible Exchange Protocol

BPEL - Business Process Execution Language

E-Business XML

REST - Representational State Transfer

SOAP - outgrowth of XML-RPC , originally an acronym for Simple Object Access Protocol

UDDI - Universal Description, Discovery, and Integration

WSDL - Web Services Description Language

WSFL - Web Services Flow Language (superseded by BPEL )

WSCL

XML-RPC - XML Remote Procedure Call

XML

Stands for “Extensible Markup Language”

Language specification for describing data

Syntax rules

Syntax & Grammar for creating Document Type Definitions

Widely used and open standard

Defined by the World Wide Web Consortium (W3C)

http://www.w3.org/TR/2000/REC-xml-20001006

Advantages of WebServices

Allow programs written in different languages on different platforms to distribute an application in a standards-base manner.

Adapt the loosely coupled Web programming model for use in applications that are not browser based.

The goal is to provide a platform for building distributed applications using software

- running on different operating systems and devices,

- written using different programming languages and tools from multiple vendors,

- all potentially developed and deployed independently.

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Web Service security

Web Service Security Model Principles

WS-Security

WS-Policy

WS-Trust

WS-Privacy

WS-SecureConversation

WS-Federation

WS-Authorization

Microsoft Passport Service – Single click sign-on!

Future….

Semantic Web Services

Extension of the current web – information is given well-defined meaning

Contains machine readable instructions and metadata expressed

in RDF.

Leads to intelligent web.

Part - II Microsoft .NET

What is .NET

It is the combination of:

.NET Framework

Web Services

.NET Enterprise Servers

The .NET Framework consists of:

The common language runtime

Class libraries, organized into easily comprehensible namespaces

ASP.NET

.NET Framework Operating System Common Language Runtime Base Class Library ADO.NET and XML ASP.NET Web Forms Web Services Mobile Internet Toolkit Windows Forms Common Language Specification VB C++ C# JScript J# Visual Studio.NET

C# (pronounced as C Sharp)

C# is a strongly typed object-oriented language from Microsoft.

designed to give the optimum blend of simplicity, expressiveness, and performance.

Released by June 2000.

The C# language was built with the hindsight of many languages, but most notably Java and C++.

It was co-authored by Anders Hejlsberg and Scott Wiltamuth

Hello World using System; class Hello { public static void Main() { Console.WriteLine("Hello, World!"); } }

The Common Language Runtime Compilation and Execution Compilation Before installation or the first time each method is called Execution JIT Compiler Native Code MSIL Code Metadata Source Code Language Compiler

Gerard Sylvester Questions? [email_address] http://germic.blogspot.com http://www.gerardsylvester.com